The Trials of Hypertension Prevention (TOHP) is a collaborative multicentered research program designed to test the feasibility and short-term effectiveness of selected nutritional and behavioral non-pharmacologic interventions in reducing or preventing an increase in diastolic blood pressure (DBP) in normotensive individuals. The information regarding the efficacy, safety and feasibility of the multiple interventions tested in Phase I would be used to assess the potential benefit of proceeding to a full-scale trial, Phase II, the objective of which would be to determine the effectiveness of the most promising of these therapies in reducing the incidence of frank hypertension. As the Coordinating Center, in conjunction with the Planning Committee, we would play a collaborative role in the design, conduct and analysis of the trial. During the 9-month planning period (Phase 1A), our major responsibility would be to coordinate the efforts of the Planning Committee in preparing for the start-up of the trial at the clinical centers. Specific activities would include the development of standardized trial materials including the study protocol, data forms, and a detailed Manual of Operations, as well as the training and certification of clinical center personnel. We would also assume responsibility for designing and implementing data processing and management programs. During the implementation period (Phase 1B), the Coordinating Center would be responsible for integrating the activities of the various collaborating units of the study (e.g., clinical centers, central laboratory, NHLBI). Major functions would include: (1) the collection, receipt, quality control, and analysis of data; (2) serving as the major interface with the clinical centers; and (3) facilitating the activities of all supervisory committees. Thus, the Coordinating Center will serve a proactive and collaborative role as an epidemiologic, statistical, clinical, and data management resource.